The present invention relates to method and apparatus for jumpering resistors and other components on a printed circuit board. More specifically, the present invention relates to a small clip or shoe box shaped jumper adapted to fit snugly over a component to create a short between terminals of the component.
In the electronic arts, it is common to attach components to a printed circuit board (PCB). Typically the PCB contains a plurality of layers that carry PCB traces between contact points on the board. One common prior art technique used to attach components to a PCB is to provide a series of holes in the board, with the traces providing conduction paths between holes. When the PCB is assembled, components having leads or pins are inserted into the holes and soldered to the PCB. One of the disadvantages of this technique is that traces cannot be routed in any of the layers at the location of the hole.
More recently, it has become common to mount components to the surface of the PCB. This technique is known in the art as xe2x80x9csurface mount technologyxe2x80x9d (SMT). FIG. 1 shows a prior art configuration 10 wherein an SMT component 12, such as a resistor, is mounted to a PCB 14. Component 12 includes conductive ends 15, which are the terminals of the component. When component 12 is assembled to PCB, the component is placed on the PCB and soldered in place using a technique such as a wave solder operation. The result is a pair of solder fillets 16 formed by surface tension interactions between the terminals, solder and PCB. One of the advantages of this technique is that PCB traces can be routed under solder fillets, thereby increasing PCB routing efficiency.
In the art, it is known to have a single PCB design support a variety of configurations. For example, a computer system motherboard may support several CPUs that each operate at unique voltages and clock frequencies. Of course, one technique is to design and manufacture several variations of the board. This approach is expensive because it requires additional design time, and extra configurations and inventories must be managed.
Another approach is to provide some type of configuration mechanism on the board. One common method is mount a series of dual in-lin package (DIP) switches to the board. DIP switches are relatively expensive, and are often mounted to the board using through hole mounting techniques, as discussed above. Furthermore, DIP switches require a relatively large amount of space on the board, and require at least a pair PCB traces for each switch. The switches are used to perform such functions as selectively coupling a configuration pin of an integrated circuit (IC) to a high or low voltage, switch resistors into or out of a voltage divider that is used to generate a reference voltage, alter a multiplier or divider that is used to generate a clock signal, and the like. Often the DIP switches are set once, and are never touched again for the life of the product.
A similar technique is to mount a series of pin headers to the PCB. Pin headers are typically mounted using through hole techniques. Jumpers are then placed over the pin headers to selectively make or break a connection between the pins. The jumpers are comprised of a small plastic box having an open end, with a piece of conductive metal having two curled ends positioned in the box. When the jumper is placed over a pair of pins, the curled metal ends surround the pins.
Both DIP switches and headers/jumpers require board traces and typically through holes. Furthermore, the PCB must be designed to accommodate these devices before the PCB is manufactured. What is needed in the art is an inexpensive and simple method to configure a PCB without requiring through holes, additional PCB traces, and additional space on the PCB, and that also has the potential to provide PCB configuration options that were not anticipated when the PCB was designed.
The present invention is a conductive clip that can be placed over a component mounted to a printed circuit board (PCB), thereby providing a conductive path between terminals of the component to bypass the component. By designing a PCB to use the present invention, dual in-lin package (DIP) switches and headers/jumpers can be eliminated.
The present invention does not require any additional space on a PCB, and does not require any additional PCB traces, thereby reducing PCB cost. In addition to reducing the cost of a PCB, the conductive clips themselves are much less expensive than either DIP switches or headers/jumpers, thereby reducing costs even further.
In one embodiment, a conductive clip in accordance with the present invention is placed over a surface mount technology (SMT) component. In this embodiment, the clip includes a cylindrical member that provides additional resilient force to urge the ends of the clip into contact with the ends of the component. The cylindrical member also provides a convenient xe2x80x9chandlexe2x80x9d to allow an assembler to position the clip onto the component, and to remove the clip by inserting a small tool into the cylindrical member and prying the clip away from the component. Each clip end also includes a flared portion and a sharp triangular retainment detent. The flared portion maximizes contact with a solder fillet and allows the flared portion to slide down over the fillet and snugly into place. The retainment detent is disposed to allow the clip to be easily positioned onto the component, while also retaining the clip in place, and also provides an additional reliable point of electrical contact between the clip and the terminal of the component.
In another embodiment, the clip has a shoe box shape and includes two sides having retainment detents. These retainment detents are disposed to slide under SMT components that have a center section not in contact with the PCB, or engage an area between a beveled edge of the component and the PCB.
Another embodiment of the present invention is adapted for use with through hole mounted components having axial leads. In this embodiment, the end of each clip includes a slot that engages the leads when the clip is pressed onto the component.
The present invention allows a PCB to be designed to support multiple configurations without using DIP switches or headers/jumpers. The present invention does not require any additional space on a PCB, and does not require any additional PCB traces, thereby reducing PCB cost. In addition to reducing PCB costs, the conductive clips themselves are much less expensive than either DIP switches or headers/jumpers, thereby reducing costs even further. Finally the present invention can be used to alter circuits in ways that were not anticipated when the PCB was designed.